Accompanying the miniaturization of LSI in recent years, Process Proximity Effects (PPE) has been actualized, PPE meaning a phenomenon that a pattern can not be transcribed onto a wafer as a design pattern in a process (lithography process) etc. of forming a design pattern to an exposure original plate (mask or reticulum) without change, transcribing in reduced size it to the water via an exposure device and forming a resist pattern. Therefore, Process Proximity Correction (PPC) has been needed, where PPC means a technology that the pattern after the transcription can be shaped as the desired design pattern by using a mask pattern corrected in the pattern dimension and the shape.
For the PPC, a method of forming mask data is proposed, the method including that the design data are corrected and the mask data are formed. This method is, for example, disclosed in JP-A-H11 (1999)-102062.
In the method of forming mask data, the mask data is formed by that such corrections as an etching process correction, a lithography process correction and a mask process correction are applied sequentially to the design data in this order.
However, according to the method of forming mask data, corrections are performed based on planar (two-dimensional) shapes of patterns formed in each process step so that it is difficult to predict the shapes with a high degree of accuracy. For example, resist shapes and fabrication shapes to be needed at the etching process correction are regarded as planar shapes so that it is difficult to reflect variations of the fabrication shapes according to cross-sectional shapes of the resist. On the other hand, if three-dimensional shape data are used, the processing time becomes lengthened.